1. Field of the Invention
The present invention relates to a semiconductor laser device and a manufacturing method of the semiconductor laser device.
2. Background Arts
Japanese Patent Application Laid-Open No. H5-029703 discloses a semiconductor laser device including a diffraction grating. As a method for forming a diffraction grating, an electron beam exposure is known. When a diffraction grating is formed on a wafer using the electron beam exposure, a portion where no diffraction grating is lithographed is provided between adjacent diffraction gratings along an optical waveguide of the diffraction grating. When the wafer is cleaved to form respective devices and the optical grating extends in the cleaved facet of the device, the optical grating terminated at the cleaved facet degrades the performance of the whole device. On the other hand, when a portion where no diffraction grating is lithographed is provided between the diffraction gratings, conditions to grow semiconductor layers on the diffraction grating become inhomogeneous between an area where the diffraction grating is formed and another area where no diffraction grating is formed, which may cause or arise defects arising from a boundary between two areas. When such defects are arose in the device, luminescent efficiency of the semiconductor laser device degrades.